AU2009294831B2

AU2009294831B2 - Device for separating ferromagnetic particles from a suspension

Info

Publication number: AU2009294831B2
Application number: AU2009294831A
Authority: AU
Inventors: Vladimir Danov; Bernd Gromoll
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2008-09-18
Filing date: 2009-07-20
Publication date: 2012-12-13
Anticipated expiration: 2029-07-20
Also published as: US20120012512A1; PE20110531A1; AU2009294831A1; CN102159320A; CN102159320B; CA2737506C; DE102008047841B4; CA2737506A1; DE102008047841A1; WO2010031616A1; US8357294B2

Abstract

The invention relates to a device for separating ferromagnetic particles from a suspension. Said device comprises a tubular reactor having at least one magnet, a suspension being able to flow through the reactor. A displacer (9) is arranged inside the reactor (2).

Description

PCT/EP2009/059308 - 1 2008P07779WOUS Description Device for separating ferromagnetic particles from a suspension The invention relates to a device for separating ferromagnetic particles from a suspension, comprising a tubular reactor through which the suspension can flow and which has at least one magnet. In order to extract ferromagnetic components which are contained in ores, the ore is ground into a powder and the powder obtained is mixed with water. A magnetic field generated by one or more magnets is applied to this suspension, as a result of which the ferromagnetic particles are attracted so that they can be separated from the suspension. DE 27 11 16 A discloses a device for separating ferromagnetic particles from a suspension, in which a drum consisting of iron rods is used. The iron rods are alternately magnetized during the rotation of the drum, so that the ferromagnetic particles adhere to the iron rods while other components of the suspension fall down between the iron rods. DE 26 51 137 Al discloses a device for separating magnetic particles from an ore material, in which the suspension is fed through a tube which is surrounded by a magnetic coil. The ferromagnetic particles accumulate at the edge of the tube, while other particles are separated through a central tube which is located inside the tube. A magnetic separator is described in US 4,921,597 B. The magnetic separator comprises a drum, on which a multiplicity of magnets are arranged. The drum is rotated oppositely to the flow direction of the suspension, PCT/EP2009/059308 - 2 2008Po7779WOUS so that ferromagnetic particles adhere to the drum and are separated from the suspension. A method for the continuous magnetic separation of suspensions is known from WO 02/07889 A2. This uses a rotatable drum in which a permanent magnet is fastened, in order to separate ferromagnetic particles from the suspension. In known devices, a tubular reactor, through which the suspension flows, is used to separate the ferromagnetic particles from the suspension. One or more magnets, which attract the ferromagnetic particles contained in it, are arranged on the outer wall of the reactor. Under the effect of the magnetic field generated by the magnets, the ferromagnetic particles migrate onto the reactor wall and are held by the magnet arranged on the outside of the reactor. Figure 1 shows the profile of the force of attraction as a function of the radial position in a conventional device. The distance from the middle of the reactor is plotted on the horizontal axis, the dot and dash line corresponding to the midline of the reactor. The force of attraction is plotted on the vertical axis. The force of attraction, which is proportional to the magnetic field gradient, has a parabolic profile, is minimal at the center of the reactor and maximal on the inner wall of the reactor. Accordingly, particles which are located in the middle of the reactor are not attracted, or only partially attracted, by the magnet or magnets and subsequently separated from the suspension. In particular with high speeds, this effect means that a considerable part of the suspension flowing through the reactor is not attracted to the inner wall of the reactor, and leaves the reactor again without the ferromagnetic particles being separated. For this reason, the separation ratio in conventional devices is unsatisfactory with significant flow rates.

3 Object of the Invention It is the object of the present invention to substantially overcome or ameliorate one or more of the above disadvantages. Summary of the Invention The present invention provides a device for separating ferromagnetic particles from a suspension, the device comprising a tubular reactor through which the suspension can flow, wherein a displacer is arranged inside the reactor, and wherein the reactor has at least one suction line branching off from the reactor, to which a negative pressure can be applied and which is surrounded by a permanent magnet in the region of the branching. Preferably, the flow cross section of the device is annular, which is achieved by the displacer arranged centrally inside the reactor. The effect of the displacer is that the suspension flowing through the reactor flows close to the wall of the reactor, so that virtually all the ferromagnetic particles lie in the region of influence of the magnetic field or magnetic fields. Preferably, the displacer is formed as a tube. Separated ferromagnetic particles can be extracted through the suction line and thereby separated from the suspension. The device according to the invention therefore has the advantage that the reactor does not need to be stopped in order to remove the ferromagnetic particles from the suspension. Accordingly, the PCT/EP2009/059308 - 4 2008P07779WOUS separation of the ferromagnetic particles can be carried out continuously with the device according to the invention. According to a refinement of the invention, the permanent magnet may be surrounded by a coil winding which allows magnetic field control. The magnetic field of the permanent magnet can be increased or decreased by the magnetic field control. In this way, it is possible to adapt the region of influence inside which ferromagnetic particles are attracted, and subsequently separated from the suspension via the suction line. The device according to the invention may particularly advantageously comprise a plurality of suction lines arranged successively in the flow direction, each of which is surrounded by a permanent magnet in the region of the branching. The plurality of suction lines may be arranged in cascade fashion in the flow path of the suspension, so that further ferromagnetic particles are removed from the suspension as the suspension flows through the reactor. The device according to the invention may also comprise a plurality of suction lines arranged distributed in the circumferential direction of the reactor, each of which is surrounded by a permanent magnet in the region of the branching. With such an arrangement, virtually the entire flow cross section can be exposed to a magnetic field so that a very large fraction of the ferromagnetic particles contained in the suspension can be removed from the suspension by means of the suction lines. It is particularly preferable for the suction line of the device according to the invention, and preferably each suction line, to comprise a controllable shut-off valve. Each shut-off valve can be opened and closed by a control device. When a shut-off valve is opened, the ferromagnetic particles which PCT/EP2009/059308 - 4a 2008P07779WOUS have accumulated under the effect of the magnetic field PCT/EP2009/059308 - 5 2008P07779WOUS enter the suction line owing to the negative pressure and can be collected at another position. The negative pressure may, for example, be generated by a pump or the like. A plurality of suction lines may also be connected together. Suction lines connected together can be used simultaneously to suction accumulated ferromagnetic particles by opening the associated shut-off valves simultaneously. If a plurality of suction lines are connected together, a single negative pressure generation device, for instance a pump, is sufficient in order to suction the ferromagnetic particles from all the suction lines. Other advantages and details of the invention will be explained with the aid of exemplary embodiments with reference to figures. The figures are schematic representations, in which: Fig. 1 shows a diagram in which the force of attraction as a function of the radial position is represented for a conventional device; Fig. 2 shows a first exemplary embodiment of a device according to the invention; and Fig. 3 shows a second exemplary embodiment of a device according to the invention. The device 1 shown in Fig. 2 comprises a tubular reactor 2, which has a plurality of suction lines 3. The reactor 2 has a plurality of suction lines 3 arranged successively in the flow direction; two suction lines 3 lie opposite one another in each case. Each suction line 3 is surrounded by an annularly formed permanent magnet 4. Each permanent magnet 4 is surrounded by a PCT/EP2009/059308 - 5a 2008P07779WOUS coil winding 5, with which the magnetic field generated by PCT/EP2009/059308 - 6 2008P07779WOUS the permanent magnet 4 can be amplified or attenuated. The coil windings 5 are connected to a control device (not shown). Each suction line 3 can be closed and opened by means of a shut-off valve 6. The various suction lines 3 open into suction lines 7, in each of which there is a pump generating a negative pressure. A displacer 9 is arranged centrally inside the reactor 2. In the exemplary embodiment represented, the displacer 9 is formed as a tube, although in other exemplary embodiments it may also be formed as a solid cylinder. Owing to the displacer 9, the flow cross section in the device 1 shown in Fig. 2 is annular. Even if the magnetic particles lie on the surface of the displacer 9, they are subjected to the effect of the magnetic field generated by the permanent magnets 4, so that the ferromagnetic particles are attracted toward the permanent magnet 4 and adhere at this position. The arrows in Fig. 2 indicate the flow direction of the suspension. A suspension 11 is applied to the inlet 10 of the reactor 2. This suspension consists of water, ground ore and optionally sand. The particle size of the ground ore may vary. Under the effect of the magnetic fields of the permanent magnets 4, ferromagnetic particles 12 are deposited on the inner side of the reactor in the region of the permanent magnets 4, as shown in Fig. 2. These deposits form on all the permanent magnets 4, which are arranged successively in the flow direction in the reactor 2. When the shut-off valves 6 are opened - as shown in Fig. 2 - the ferromagnetic particles pass through the suction lines 6, owing to the negative pressure generated by the pump 8, into suction lines 7, so that the ferromagnetic particles can be separated from the suspension 11 PCT/EP2009/059308 - 7 2008PO7779WOUS and collected in a storage container. The strength of the magnetic fields of the permanent magnets 4 can be controlled by means of the coil windings 5, that is to say the magnitude of the magnetic fields can be increased or decreased. The suction of the ferromagnetic particles takes place with a reduced magnetic force by the coil windings 5 being controlled accordingly. Other non-ferromagnetic particles, which are contained in the suspension, or other components such as sand, flow axially through the reactor 2 without being affected. Fig. 3 shows a second exemplary embodiment of a device for separating ferromagnetic particles from a suspension, components which are the same being provided with the same references. The device 13 consists of a reactor 2, inside which there is a centrally arranged displacer 9. A plurality of suction lines 3 open radially in the shape of a star into the reactor 2. In the region of the branching of the suction lines 3 from the reactor 2, there are segmentally arranged permanent magnets 4. The permanent magnets 4 are segment-polarized. In accordance with the device shown in Fig. 2, each suction line 3 is provided with a controllable shut-off valve 6. By means of a negative pressure generation device (not shown in Fig. 3), for instance a pump, with open shut-off valves 6 the magnetically separated part can be suctioned from the suspension and subsequently removed. In Fig. 3, it can be seen that the suspension 11 is located in an annular gap between the outer side of the displacer 9 and the inner side of the reactor 2. With the device 13, a high separation ratio and therefore a good yield can be achieved even with significant flow rates.

Claims

1. A device for separating ferromagnetic particles from a suspension, the device comprising a tubular reactor through which the suspension can flow, wherein a displacer is arranged inside the reactor, and wherein the reactor has at least one suction line branching off from the reactor, to which a negative pressure can be applied and which is surrounded by a permanent magnet in the region of the branching.

2. The device as claimed in claim 1, wherein the displacer is arranged centrally inside the reactor.

3. The device as claimed in claim I or 2, wherein the displacer is formed as a tube.

4. The device as claimed in any one of the preceding claims, wherein the permanent magnet is surrounded by a coil winding which allows magnetic field control.

5. The device as claimed in any one of the preceding claims, wherein the device comprises a plurality of suction lines arranged successively in the flow direction, each of which is surrounded by a permanent magnet in the region of the branching.

6. The device as claimed in any one of the preceding claims, wherein the device comprises a plurality of suction lines arranged distributed in the circumferential direction of the reactor, each of which is surrounded by a permanent magnet in the region of the branching.

7. The device as claimed in any one of the preceding claims, wherein the or each suction line comprises a controllable shut-off valve.

8. The device as claimed in any one of the preceding claims, wherein a plurality of suction lines are connected together. 9

9. A device for separating ferromagnetic particles from a suspension, the device being substantially as hereinbefore described with reference to any one of the embodiments of the device as that embodiment is shown in Figures 2 and 3 of the accompanying drawings. Dated 30 October 2012 Siemens Aktiengesellschaft Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON